Fixing typo in comment blocks of createError() and enhanceError()

[martinjoiner]

Nothing more than a couple of typos in the comment blocks of 2 functions. I'm only fixing this because they were being picked up by the code linter in my pre-commit hook in my webpack-built Laravel 5 project.

[coveralls]

Coverage increased (+1.5%) to 93.719% when pulling 30c5a3b on martinjoiner:master into f31317a on mzabriskie:master.

[rubennorte]

Thanks for the fixes!